Primarily for general aviation discussion, but other aviation topics are also welcome.
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#1682135
MichaelP wrote:
I would never rely on a software fix to an aerodynamic problem.
Put a tailplane and elevator on the aeroplane that is capable of ensuring stability and I would be happy.
Computerised stability in fighters, B2 bombers, and UAVs is one thing, but in passenger aircraft where aerodynamic stability is needed, they should be unnecessary.



This might have been true fifty years ago, but these days fuel efficency is the master. Tail surfaces are reduced to the minimum area, fuel is transfered aft in cruise to shift the c of g and achieve a minimum drag stabiliser angle, and artificial stability and envelope protection are the norm.

The last airliner I flew, the Boeing/McDonnell Douglas MD11, was such a flying pig, partly because of the undersized tailplane, that it had no less than 4 yes 4! Longitudinal Stability Augmentation Systems, that were pushing and pulling 'behind the scenes' to make the beast handle acceptably in pitch. At least their function was documented in the manuals, unlike this latest Boeing product...
AlanM, Rob P, Flyin'Dutch' and 1 others liked this
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By neilmurg
#1682145
As I said before:
It's not a Boeing/Airbus thing, when you push developments you occasionally reveal a flaw you didn't predict.
Airbus FBW has had issues in the past. I hope/expect that Airbus won't make the same cheap shots that Boeing have.
It may however put a dent in 737 sales, they really need to redevelop the wing, or maybe the whole plane, fbw?
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By kanga
#1682186
On a lighter note ..

Just visible on the front page of today's FT, here:

https://www.bbc.co.uk/news/blogs-the-papers-47577815

.. is a headline reading

"Boeing Max costs spur rush to hedge"

.. sounds like brake failure ? :)
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By PaulB
#1682254
This piece in The Atlantic, suggests that rather than ground the jets, it’s the pilots who should have been grounded until they’d undergone training in how to overcome this issue.

(It also talks about potential design deficiencies too....)

https://www.theatlantic.com/notes/2019/ ... ts/584941/
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By flyguy
#1682279
PaulB wrote:This piece in The Atlantic, suggests that rather than ground the jets, it’s the pilots who should have been grounded until they’d undergone training in how to overcome this issue.

(It also talks about potential design deficiencies too....)

https://www.theatlantic.com/notes/2019/ ... ts/584941/


Fascinating article. Talking to a senior pilot in the US who recently underwent the 737 Max Type Rating, he confirmed that there was NO description in the Flight Manual about MCAS and that NOTHING was mentioned about it during 737 differences training.
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By mortweaver
#1682462
The two Boeing 737 Max aircraft involved in fatal accidents were flown by non US based airlines. It will
be interesting to learn if the tragic loss of life is at all related to inadequate training.
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By skydriller
#1682479
mortweaver wrote:The two Boeing 737 Max aircraft involved in fatal accidents were flown by non US based airlines. It will
be interesting to learn if the tragic loss of life is at all related to inadequate training.


Having just seen the Air Crash Investigation* show about the American A300 rudder over-stress accident, it isnt just outside the US that inadequate training is a possible problem.

Regards, SD..

*I seem to be having a bit of a binge on these, most of which I havent seen before - National Geographic channel is showing 2 of these per weekday night right now...
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By Gertie
#1682480
MichaelP wrote:The instability of the 737 Max series

Are there any other unstable aircraft for which it is possible to buy a passenger ticket?

Could the flight booking web sites have a "do not book me onto an unstable aircraft" check box?
#1682517
skydriller wrote:Having just seen the Air Crash Investigation* show about the American A300 rudder over-stress accident, it isnt just outside the US that inadequate training is a possible problem.
*I seem to be having a bit of a binge on these, most of which I havent seen before - National Geographic channel is showing 2 of these per weekday night right now...
Me 2, although I also tend to look up the accident report during the first 30 minutes as the NTSB chaps exchange worried 'daytime TV' type glances at each other as they chase the obligatory 3 wrong leads before the final reveal.
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#1682540
A few years ago I was in and out of a place named Dobbins.
There they had stretched the C130 and added smaller diameter Dowty propellers.
The J had a terrible stall I was told, with the vision of one rolling off a stall when on final for a short field...
This had to be fixed aerodynamically before the aircraft could be delivered to the RAF among others.
Mind you RAF pilots really wanted the Globemaster.

Artificial computerised stability and control will revolutionise efficient air transportation as it has allowed flying wing UAVs and B2 bombers. But when it does there will be no need for human pilots as these fallible beings will no longer be able to control the aeroplane with conventional control inputs.
This system in the 737 Max is the beginning of the wedge. It’s a system that necessarily over-rides the pilot due to a dangerous instability in the aircraft that can too easily occur.
Fix the aerodynamics and you give the pilot half a chance of being able to fly the aeroplane.
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By Gertie
#1682546
MichaelP wrote:This system in the 737 Max is the beginning of the wedge. It’s a system that necessarily over-rides the pilot due to a dangerous instability in the aircraft that can too easily occur.

I understand why fighter aircraft are unstable - they're deliberately designed that way for good reason.

But what I can't understand is why an airliner would be unstable for any reason other than c r a p design?
Last edited by Gertie on Sat Mar 16, 2019 10:40 pm, edited 1 time in total.
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By Korenwolf
#1682677
Well, we can all stop speculating....Nick Ferrari in today's Sunday Express has the answer.

No link, so quoting verbatim -

"Having taken to the skies in 1964, 10,000 Boeing 737s have been built and they were one of the most reliable of workhorses. However, the 737-800 MAX had its first commercial flight less than two years ago and already two have met catastrophic ends. In October, all 189 people died when one plunged into the Java Sea, and last week all 157 on board were killed when another crashed in Ethiopia.
This new version was to satisfy environmental concerns and aimed to cut fuel consumption by 30 percent. To make it work, two engines that were so big they couldn't go under the wings were slung in front of them, which obviously radically affects the gravity of the aircraft. This was the first time Boeing had attempted this.
it will take months for detailed reports to be filed. However, we are continually told by the green zealots that lives could be being lost due to climate change and the fact we are not being suitably environmentally conscious. Try telling that to the families of those who died on these "super green" jets."

That's all sorted then....
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